Bioflavonoids are a group of naturally occurring compounds and are widely distributed among plants, including most all citrus fruits, rose hips and black currants. Such compounds are generally isolated from the rinds of oranges, tangerines, lemons, limes, kumquats and grapefruits by commercial extraction methods.
Bioflavonoids have been determined to be involved with homeostasis of the walls of small blood vessels. In addition, these compounds have been found to contribute to the maintenance of normal blood vessel conditions by decreasing capillary permeability and fragility. Bioflavonoids have also been found to have activity as a histamine release blocker (treatment of allergies), a xanthine oxidase inhibitor (treatment of gout), an aldose reductase inhibitor (prevention of diabetic complications), a phospholiphase A2 and lipoxygenase inhibitor (anti-inflammatory), an aerobic glycosis inhibitor (an anti-cancer agent), and a tumor necrosis factor potentiator (an antiviral agent.
However, despite their promise for a variety of medicinal applications, the utility of bioflavonoids have been limited by their poor absorption into the bloodstream due, at least in part, to their low solubility under physiological conditions. For example, quercetin (i.e., 3,3',4',5,7-O penta-hydroxyflavone), has been the subject of extensive study, and has the following structure ##STR1##
Quercetin is absorbed to the extend of about 1% from an oral dose. Effective cellular uptake of quercetin appears to require the use of water-miscible solvents such as dimethylsulfoxide. Furthermore, while other bioflavonoids have been found to be more soluble than quercetin under physiological conditions, these compounds appear to be less effective than quercetin.
Chalcones, a class of bioflavonoids, have shown promise in overcoming the limitations of other bioflavonoid compounds, and have the following general structure. ##STR2## Although chalcones generally have high solubility and absorption under physiological conditions (e.g., hesperidin methyl chalcone, a representative class member, is absorbed to the extend of 60% from an oral dose), their activity is significantly less than that of similar bioflavonoids such as quercetin. This greater solubility and absorption of chalcones may be attributed to their increased solubility through substituents such as sugar moieties present in some chalcones and absent in quercetin. The greater solubility and absorption of chalcones thus appears to be at the expense of biological activity.
Accordingly, there is a need in the art for a soluble, bioavailable bioflavonoid that also possesses high bioactivity. The present invention fulfills these needs and provides further related advantages.